I don't know anyone with COPD. It sounds ugly, though. My only advice is that, while you may not be able to do all you wish or all you once did, you should be able to learn what your body is willing and able to accomplish, keep your hiking goals within your physical limits, and still get out there.
When my brother was afflicted with Type I diabetes at age 12, the usual medical advice was very restrictive and confining. Instead, he developed his own methods and kept on camping hiking with our family, and later backpacking in very remote places. A few years ago, in his early 60s and after bypass surgery, he and I still shoehorned in a couple of backpacks trips together. So, don't despair.
If your family worries about you being in the backcountry, get a PLB or a SPOT messaging unit, so they'll, uh, breathe a bit easier.